Takes only a few minutes to simply loosen the pulley bolt and add a little tension to the belt. I'd say it's certainly a lack of tension causing the squeal. What kind of condition is the belt in? There's also no reason to replace the crank pulley unless it's damaged in some kind of way.

 

I have had the same issue on mine. It was the belt tension. I was surprised how much tension these belts require to not squeal. I now carry the socket, and wrench in the Jeep so I can adjust the tension whenever.

Like others have suggested, turn it a few flats. Drive, repeat as necessary.